Immunocytochemical differences in adenohypophyseal cells among adult Mongolian pony mares, stallions, and geldings.

This study found that there are sex-related differences in specific hormonal cells in the pituitary gland of adult ponies, with stallions having more somatotrophs and mares having more FSH, LH cells and lactotrophs. Also, geldings neutered before puberty show a significant change in the proportion of these cells.

Research Purpose and Methodology

• The aim of this study was to identify if any sex-based variation exists in the presence of six specific adenohypophyseal cells in adult Mongolian ponies.
• Additionally, the study sought to establish if prepubertal orchidectomy, also known as castration, makes any significant difference to these cells.
• To investigate, pituitary glands were collected from 15 adult Mongolian ponies aged between 5 and 10 years, with 5 each from stallions, mares and geldings which were neutered between 1 and 2 years of age.
• Immunocytochemistry and morphometry were utilized to observe and compare the morphology of the six kinds of adenohypophyseal cells among the different sex classes.

Findings

• Statistical significance was found between the genders with regard to the population of somatotrophs, gonadotrophs (FSH and LH cells), and lactotrophs in adult ponies.
• Somatotrophs were more prevalent in stallions compared to mares.
• FSH and LH cells, and lactotrophs were more common in mares as against stallions.
• Prepubertal orchidectomy noticeably lessened the proportion of somatotrophs and raised that of lactotrophs in geldings, in comparison with stallions.
• The area occupied by LH cells was found to be larger in mares than in stallions.
• Prepubertal orchidectomy enlarged both FSH and LH cell areas in geldings when compared with stallions.

Conclusions

• Clear sex-based differences exist in adenohypophyseal cells of adult ponies, with somatotrophs being more abundant in stallions while FSH and LH cells along with lactotrophs being more abundant in mares.
• The researchers propose that equine testes might stimulate the development of GH cells, while suppressing the development of FSH and LH cells alongside lactotrophs during postnatal life.
• Interestingly, the impact of prepubertal orchidectomy on somatotrophs and lactotrophs in ponies greatly differs from its effect on similar cells in mice, implying that the effect of such procedure can be species-specific.